Belemnite ( Cylindroteuthis puzosiana ) showing ventral groove

Cylindroteuthis puzosiana most common of the Belemnites found in the Oxford Clay.

GEOLOGIC AGE: Middle Jurassic. 160 million years old.

STRATIGRAPHIC DETAIL: Lower Oxford Clay. Callovian Stage.

LOCATION: Peterborough, Cambridgeshire, UK.

Description: Large rostrum, commonly attaining a length of 150-170mm but reaching a maximum of approximately 240-250mm. Rostrum cylindrical to cylindriconical, and symmetrical or almost symmetrical in outline ( lateral aspect ) and profile ( ventral or dorsal aspect ).The apex is acute, although in some examples it may be rounded. Transverse sections of the rostrum are slightly compressed and sub circular to sub quadrate in form, often with a flattened venter. A sharply defined ventral groove is restricted to the apical quarter of the rostrum. Indistinct elongate depressions (lateral lines) are present on both flanks, and are especially well-defined in juvenile examples. The phragmocone is frequently absent from the alveolus, which penetrates up to one-quarter of the length of the rostrum.